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    October 2013 Run Day 4: Phasing Tests on Several Stars

    On Friday October 18 we had a half night scheduled for LMIRCam science, followed by a half night for phase sensing engineering. The LMIRCam observations went smoothly and had good conditions.

    For phase engineering, we saw significantly more phase variation with our revised loop algorithm (see last post). The phase variations appeared to be nearly +/- 180 degrees per frame at 2 microns. This suggests a vibration problem. We tried shutting off
    • our own compressor, turning off
    • the mirror ventilation
    • the facility chiller
    • turning down the AO gain.
    None of these seemed to affect the phase variations. So, we took as much data we could. We acquired:
    • 10 micron nulling data at 30 Hz (see plot from Denis Defrere below)
    • 2 micron phase data at 500 Hz (data still being analyzed)
    • 4 micron dispersed fringe data at 3 Hz (shows large pathlength motions)
    As the plot shows there seems to be some vibration at 10 Hz, but 200 nm is about 1/10 of a wave at 2 microns, while the 2 micron data (the error signal for our control loop) seemed to be showing up to 500-1000 nm variations. For the moment, it's a mystery what's going on until we complete the data analysis.


    Saturday through Monday observations are LMIRCam science, so we have a couple days to determine our next step for phase sensing. We will resume tests on Tuesday night.


    Comments

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    Taquarius Ford (unauthenticated)
    Nov 29, 2013

    by: Taquarius Ford

    What a great read. I can't wait to read the finished product.

    /groups/lbti/search/index.rss?tag=hotlist/groups/lbti/search/?tag=hotWhat’s HotHotListHot!?tag=hot1/groups/lbti/sidebar/HotListAdded tag - hotphinzPhil Hinz2010-10-15 20:37:53+00:002010-10-15 20:37:53addTag3phinzPhil Hinz2010-10-15 13:18:40+00:002010-10-15 13:18:40updated2First createdphinzPhil Hinz2010-10-15 13:05:39+00:002010-10-15 13:05:39created1weblog2010-10-15T13:18:40+00:00groups/lbti/weblog/b808eFalseFirst Night Results/groups/lbti/weblog/b808e/First_Night_Results.htmlPhil Hinz3 updatesFirst Night Results It was an eventful first night on the LBT. Network connections failed, hardware refused to turn on, all the typical problems of a new instrument. Aft...Falsephinz2010-10-15T13:18:40+00:00hot/groups/lbti/search/index.rss?sort=modifiedDate&kind=all&sortDirection=reverse&excludePages=wiki/welcomelist/groups/lbti/search/?sort=modifiedDate&kind=all&sortDirection=reverse&excludePages=wiki/welcomeRecent ChangesRecentChangesListUpdates?sort=modifiedDate&kind=all&sortDirection=reverse&excludePages=wiki/welcome0/groups/lbti/sidebar/RecentChangesListmodifiedDateallRecent ChangesRecentChangesListUpdateswiki/welcomeNo recent changes.reverse5searchlist/groups/lbti/calendar/Upcoming EventsUpcomingEventsListEvents1Getting events…